Method of gaining pre-cast concrete panels

ABSTRACT

Two similar, rectangular, pre-cast, concrete, vertical wall panels disposed one above the other are joined together by a joint including a horizontal plate and a vertical attachment bar. The plate is the bottom wall of a short tube extending widthwise of the lower horizontal edge of the upper panel and is anchored in this panel by means of two oblique anchoring members fixed to the plate and embedded in the panel. The bar is embedded in the lower panel and its upper end zone projects through a central aperture in the plate. A nut screwed on this zone bears downwardly on the plate via a radially slotted washer.

[451 July 25,1972

[ Clted UNITED STATES PATENTS METHOD OF GAINING PRE-CAST CONCRETE PANELS[72] Inventors: Norman Wakefield, Leatherhead; Stuart 3,226,894 1/1966Burchardtet al.....................52/223 L M 3,295,286 [/1967Schaich........................ ..........52/227 Morrlsh, GerrardsCross; William Beck, waflmghaml' hymn Sm'gis 9 Primary Examiner-R0bcrtF. White Fmham; Mkhld J- 'W- Orpmgwn. Assistant Examiner-Allen M. Sokalof England Attorney-Rosen & Steinhilper 73 A WatesLlmltedL d ,E dssignee on on nglan A CT rectangular, pre-cast. concrete, vertical wallpanels disposed one above the other are joined together by a jointincluding a horizontal plate and a vertical attachment bar. The plate isthe bottom wall of a short tube extending widthwise of the lowerhorizontal edge of the upper panel and is anchored in this panel bymeans of two oblique anchoring members fixed to the plate and embeddedin the panel. The bar is embedded in the lower panel and its upper endzone projects through a central aperture in the plate. A nut screwed onthis zone bears downwardly on the plate via a radially a m h H u .m w sd O t w m T e P Jun w n w.

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Inventors RQSEN & STEHH-NLPER my Patented July 25, 1972 3 Shouts-Shut 2NORMAN EDWARD WAKEFIELD STUART JOHN ALEXANDER JAMES FRANCIS MORRISHWILLIAM BECK RAYMOND S'IURGIS GROVES MICHAEL JAMES HARVEY,

Inventors R-:& S l, IF-q Attorneys METHOD OF GAINING PIKE-CAST CONCRETEPANELS This is a division of application Ser. No. 799,l64, filed on Feb.I4, I969, now U.S. Pat. No. 3,566,560.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a pre-cast concrete wall panel for use in the construction ofbuildings, particularly of tall buildings constructed from prefabricatedparts. The invention also concerns a method of forming the panel, anapparatus for use in the method, a method of joining together two suchpanels superimposed one on the other, and the product of the lattermethod.

2. Description of the Prior Art There is disclosed in British Patent No.1,069,488 a rectangular, pre-cast, concrete, vertical wall panel for usein the construction of a tall building. The panel has been made bycasting in a mold having two wide, opposite, lateral walls, two narrow,opposite, end walls, a narrow bottom wall, and an open top. The narrowbottom wall of the mould has an inside sur face of shallow V-section andsupports, within the mold space, two horizontal mold pieces eachextending widthwise of the narrow bottom wall from one wide lateral wallto the other. These pieces form in the lower horizontal edge of thepanel produced two openings each extending from one major face of thepanel to the other major face thereof. Each recess has a shortcylindrical extension leading vertically upwardly therefrom centrally ofthe thickness of the panel, the extension being lined by a short,vertical, metal bush partly closed at its lower end by a circular,centrally apertured washer which projects both radially inwardly of thebush and radially outwardly therefrom. The bushes and the washers areplaced on the mould pieces prior to pouring of fresh concrete into themold, and thus are pre-cast into the panel. Also pre-cast into the panelare two vertical attachment bolts coaxial with the respective bushes andprojecting with their upper end zones from the upper horizontal edge ofthe panel. These zones are screwthreaded to receive nuts.

Two such panels are superimposed one on the other with the interpositionof floor slabs and an in situ concrete stitch and a mortar bed carriedby the floor slabs and the stitch. The upper panel is lowered towardsthe lower panel until the washers of the upper panel bear on the nuts onthe attachment bars of the lower panel. Then, before the mortar bedsets, the nuts are adjusted, if necessary, to level the upper panel.After the mortar bed has set, the openings are filled with dry pack.

This known arrangement in a multi-story building in which the wallpanels are supported one upon another has the serious disadvantage thatany one of the joints between the superimposed panels relies on theweight of the panel or panels above the joint and on the adhesionbetween the mortar bed and the panels. This has been found in practiceto be insufficient in exceptional circumstances, for example in the oneof an explosion inside or outside the panel immediately above the joint,or in the case of a very high wind, where very large upward forces orvery large horizontal forces may occur. The failure of one joint in sucha building oiten leads to progressive collapse of part or all of thebuilding.

SUMMARY OF THE INVENTION According to one aspect of the presentinvention, there is provided an apparatus for use in forming a pre-castconcrete wall panel, comprising mold wall means bounding a mold spaceand open at the top for receiving unset concrete therebetween, a narrowwall of said wall means, a projection extending widthwise of said narrowwall from a longitudinal edge of said narrow wall and disposed at thewithin within said space, a joint part including in said projection,anchoring means fixed to said joint part and extending within said spacefrom said projection, d'mplaceable mold portions intervening between thecenter of said joint part and the region of said Iongitudinal edge, andsurface portions of said joint part facing said longitudinal edgefollowing displacement of said mold portions.

According to another aspect of the present invention, there is provideda method of forming a pre-cast concrete wall panel, comprising providingwithin a mold space of a mold open at the top a projection whichincludes a joint part and which extends widthwise ofa narrow wallbounding said space from a longitudinal edge of said narrow wall and isdisposed at the inside of said narrow wall within said space, alsoproviding within said mold space an attachment bar extending away fromsaid member to that side of said mold opposite said narrow wall, andanchoring means fixed to said joint part and extending within said spacefrom said projection, pouring unset concrete into said mold at the topthereof, the concrete flowing around said anchoring means, but notcontacting said joint part to a detrimental extent, and, after settingof the concrete, removing from the mold the concrete wall panel soformed having embedded therein said anchoring means, whereal'ter surfaceportions of saidjoint part facing inwardly of said panel are directlyaccessible from that side of said joint part nearer the center of thepanel by way of an opening formed in a major face ofsaid panel andextending on said side of said joint part.

According to a further aspect of the present invention, there isprovided a pre-cast, vertical, concrete, wall panel comprising aconcrete main body having upper and lower horizontal edges and twovertical major faces, a joint part disposed in said body in the regionof the lower horizontal edge of said body but projecting neitheroutwardly beyond said lower horizontal edge nor outwardly beyond saidmajor faces, an attachment bar embedded in said body and extending,through the body, away from said joint part to the upper horizontal edgeof said body, anchoring means embedded in said body and fixed to saidjoint part and extending within the body from said joint part, theconcrete of said body not contacting said joint part to a detrimentalextent, portions of said body defining an opening in one of said majorfaces extending above the level of said joint part, and uppermostsurface portions of said front part directly accessible by way of saidopening from a location above the level of said joint part and at saidone of said major faces.

According to yet a further aspect of the present invention, there isprovided a method of joining together two pre-cast, vertical, concrete,wall panels, comprising providing a first pre-cast, vertical, concretewall panel having a first concrete main body in which is embedded afirst attachment bar projecting upwardly from an upper horizontal edgeof the body, providing a second pre-cast, vertical, concrete, wall panelhav ing a second concrete main body in which h disposed a joint part, asecond attachment bar, and anchoring means, said joint part beingdisposed in the second body in the region of a lower horizontal edge ofthat body, but projecting neither outwardly beyond said lower horizontaledge nor outwardly beyond two opposite, vertical, major faces of saidsecond body, said second attachment bar being embedded in said secondbody and extending therethrough away from said joint part to an upperhorizontal edge of said second body, and said anchoring means beingembedded in said second body and being fixed to said joint part andextending within said second body from said joint part, the concrete ofsaid second body not contacting said joint part to a detrimental extent,applying a bed of unset setting material above the upper horizontal edgeof the first body, lowering said second panel towards said first panelsuch that said bed therebetween is squeezed and that said joint part isdisplaced to a location below the upper end of said first attachmentbar, and, by way of an opening in one of said major faces, fasteningsaid first attachment bar to said joint part by fastening means appliedbetween said first attachment bar and said joint part and above saidjoint part.

According to a yet still further aspect of the present inven tion, thereis provided in combination, a first pre-cast, vertical, concrete, wallpanel, a first concrete, main body of said panel having an upperhorizontal edge, a first attachment bar emaway from said joint partdirectly accessible from the region of bedded in said body andprojecting upwardly from said upper horizontal edge, a bed of setsetting material above said upper horizontal edge, a second pre-cast,vertical, concrete, wall panel, a second concrete, main body of thesecond panel having upper and lower horizontal edges and two verticalmajor faces and carried at its lower horizontal edge by said bed, ajoint part disposed in the second body in the region of said lowerhorizontal edge and below the upper end of said first attachment bar,but projecting neither outwardly beyond said lower horizontal edge noroutwardly beyond said major faces, a second attachment bar embedded insaid second body and extending therethrough away from said joint part tothe upper horizontal edge of said second body, anchoring means embeddedin said second body, fixed to said joint part and extending within saidsecond body from said joint part, and means fastening said firstattachment bar to said joint part and applied between said firstattachment bar and said joint part and above said joint part.

By means of the present invention, upward and horizontal forces on onewall panel of a multi-story building in which the wall panels aresupported one upon another are transmitted via the anchoring means tothe joint part and thence via the fastening means to the attachment barof the next panel below, and the likelihood of failure of the jointtherebetween is reduced.

BRIEF DESCRIPTION OF THE DRAWING In order that the invention may beclearly understood and readily carried into effect, reference will nowbe made, by way of example, to the accompanying drawings, in which:

FIG. 1 shows a perspective view from above of an apparatus for use informing a pre-cast, vertical, rectangular, concrete, wall panel, butwith a mold wall and mold pieces of the apparatus removed,

FIG. 2 shows a section through a detail of the apparatus,

FIG. 3 shows a partly sectional perspective view from above of a jointbetween two floor slabs and two wall panels of a building,

FIG. 4 shows a fragmentary, vertical, longitudinal, section through thejoint, and

FIG. 5 shows a fragmentary section through the joint taken on the lineV-V in FIG. 4, but with a nut and a washer displaced downwardly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, theapparatus includes particularly a mold 1 which is one of a battery ofidentical molds producing rectangular, concrete, wall panels. The mold 1comprises two wide walls 2 closed off, at the left, the right, and thebottom. by three narrow walls 3, 4, and 5, respectively, but is open atthe top for receiving fresh, i.e., unset, concrete. The mold l issupported at the bottom by horizontal beams 6 and is movably carried atthe top by rollers 7 running on horizontal beams 8. The wall 5 is ofshallow V-section and carries two identical sets of mold pieces, thesets being spaced about onequarter of the length of the mold fromrespective ends of the mold. Each set is shown in greater detail in FIG.2 and consists of three pieces 9, l0, and ll, of which the pieces 9 and[0 are identical and are disposed flushly against the inside faces ofthe respective walls 2 and flushly against the inside faces of the wall5. Each piece ll extends the whole width of the gap between the pieces 9and 10 and also abuts flushly on the inside faces of the wall 5. Theupper surface of each mold piece II is shaped to fit against theunderside of an assembly consisting of a short, horizontal, steel tube12, an internally threaded metal sleeve 13 welded to the top of the tube12, and a looped anchoring rod 14 welded to the bottom of the tube l2.Each tube 12 is arranged centrally of the width of the wall 5 and iscoaxial with the associated sleeve 13 and the associated piece ll. Ascan be seen more clearly from FIG. 4, for example, each tube 12 consistsof a thick, centrally apertured, horizontal steel plate 12a which servesas a joint part and to which is welded an inverted U-shaped thin steelcover 12b. The length of each tube 12 extends widthwise of the wall 5,and the tube has a mouth at each end which is closed by the piece 9 or10. Each rod 14 is of butterfly shape, i.e., has respective wings whichextend obliquely upwardly from the plate 12a at respective oppositesides of the tube 12. Screwed into the upper end of each sleeve [3 isthe externally threaded lower end of an attachment bar or bolt 16 whichis externally threaded also at its upper end. The upper end of each bolt16 is positioned temporarily by a bracket 17. In FIG. I, the pieces 10and l I and one of the walls 2 have been removed for clarity ofillustration.

When the apparatus has been arranged as shown in FIG. 1, fresh concreteis poured into the top of the mold l and flows about the tubes 12 andthe anchoring rods l4 but does not penetrate to a detrimental extentinto the interiors of the tubes 12, or between the tubes 12 and the wall5, because of the provision of the mold pieces 9 to 11 closing the openmouths of the tubes and the gaps between the tubes 12 and the wall 5.After filling of the mold with concrete, the latter is caused or allowedto set. The wall panel 18 (see FIGS. 3 to 5) so formed thus has firmlyembedded therein the tubes 12, the sleeves 13, the anchoring rods I4 andthe attachment bolts 16. Following withdrawal of the walls 3 and 4, thewall panel can be lifted from the mold by a lifting device applied tothe threaded upper ends of the bolts 16.

FIGS. 3 to 5 show ajoint between two pre-cast, rectangular, floor slabs19, and upper and lower vertical wall panels I8 and 18' each produced bythe method just described. The panel 18' is identical to the panel 18and thus has embedded therein two attachment bolts 16 identical to thebolts 16 and therefore having their upper ends threaded and projectingupwardly from the upper horizontal edge of the panel 18'. On this edgeare placed longitudinal edges of the floor slabs I9, and an in situconcrete stitch 20 is applied between the slabs l9 and the panel 18'. Atits top, this stitch bounds a recess 21 extending somewhat into theupper major faces of the slabs l9. Into this recess is laid a bed of wetmortar 22. Then, onto the upper ends of the bolts 16' are screwedrespective nuts 23. The panel 18 is now lowered towards the panel 18'such that the shallow V-section rib forming the lower horizontal edge ofthe panel 18 squeezes the bed of mortar 22 and that the upper ends ofthe bolts [6 and their nuts 23 are received through the centralapertures in the plates [2a, the threaded upper extremities of the bolts16' penetrating through central holes in the U-shaped covers 12 into theinteriors of the sleeves 13, but the nuts 23 remaining in the interiorsof the tubes 12. Slotted washers 24 are then placed over the nuts 23 andthe panel 18 lowered further until the covers 12b bear on the washers 24(see FIG. 4). Before lowering of the panel 18 onto the bed 22, the nuts23 have been adjusted to determine the position of the panel 18 when thepanel has been lowered onto the bed, and now the nuts 23 can be adjustedto correct the position of the panel l8 if necessary. The squeezing ofthe mortar bed 22 causes the mortar to flow upwardly into the centralapertures of the plates 12a and about the adjacent portions of the bolts16'. Any excess mortar is later removed. When the bed 22 has set, thenuts 23 are slackened, and the slotted washers 24 are withdrawn fromabove the nuts 23 and then inserted immediately below the nuts 23,whereafter the nuts 23 are tightened downwardly to press the washers 24hard against the plates 12;: and those portions of the mortar bed 22 inthe central apertures in the plates (see FIG. 5). In order that theinteriors of the tubes 12 may be directly accessible from a level abovethat of the plates 120, the openings 25 formed by the mold pieces 9 and10 in the opposite major faces of the panel 18 extend to above the levelof the plates 12a. If required, the openings 25 and the interior of thetubes 12 may be subsequently filled with dry pack, i.e., mortar with alow water content. The joint shown is for an internal wall, with whichit is preferable to have access to the joint from both major faces ofthe panel 18. However, with an external wall, it is preferred to haveaccess to the joint from only the inside major face of the panel I8, inwhich case the tubes 12 are each produced closed at one end, which willlater form its outside end, by an integral metal wall, and either thepieces 9 or the pieces 10 are omitted, so that no openings 25 are formedin the outside major face of the panel 18.

The joint described has the particular advantage that it is capable ofresisting upward forces on the panel 18 and also horizontal forces onthat panel in any direction. Any such forces on the panel 18 aretransmitted through the reinforcing rods 14 to the plates 12a and thencevia the mortar bed 22, or the washers 24 and the nuts 23, to the bolts16. The bolts 16, through being embedded in the panel 18', transfer suchforces to that panel. The arrangement shown, in which the mortar bed 22extends up to the level at which forces on the panel 18 are applied tothe bolts 16, has the advantage that the bolts [6' are thus supported asclosely as possible to that level.

Although the tubes 12 could be arranged to extend to the major faces ofthe panel 18, and thus the mold pieces 9 and 10 be omitted, thearrangement shown is preferred. Similarly, it would be possible to omitthe covers 12b, and to replace them by mold pieces during molding, whichmold pieces would be removed after forming of the panel, but, onceagain, the arrangement shown is preferred.

We claim:

1. A method of joining together two pre-cast, vertical, concrete, wallpanels, comprising providing a first pre-cast, vertical, concrete wallpanel having a first concrete main body in which is embedded a firstattachment bar projecting upwardly from an upper horizontal edge of thebody, providing a second pre-cast, vertical, concrete, wall panel havinga second concrete main body in which is disposed a joint part, a secondattachment bar, and anchoring means, said joint part being disposed inthe second body in the region of a lower horizontal edge of that body,but projecting neither outwardly beyond said lower horizontal edge noroutwardly beyond two opposite, vertical, major faces of said secondbody, said second attachment bar being fixedly embedded in said secondbody and extending therethrough away from said joint part to an upperhorizontal edge of said second body, and said anchoring means beingfixedly embedded in said second body and being fixed to said joint partand extending within said second body from said joint part, the concreteof said second body not contacting said joint part to a detrimentalextent, applying a bed of unset setting material above the upperhorizontal edge of the first body, lowering said second panel with saidsecond attachment bar and said anchoring means fixedly embedded thereintowards said first panel such that said bed therebetween is squeezed andthat said joint part is displaced to a location below the upper end ofsaid first attachment bar, and, by way of an opening in one of saidmajor faces, fastening said first attachment bar to said joint part byfastening means applied between said first attachment bar and said jointpart and above said joint part.

2. A method according to claim 1, wherein the fastening of said firstattachment bar to said joint part comprises tightening downwardly afastening nut mounted on screwthreading formed on the upper end zone ofsaid first attachment bar.

3. A method according to claim 2, wherein said fastening nut has beenmounted on said screwthreading prior to the lowering of said secondpanel towards said first panel, and, during lowering, there is passeddownwardly over said nut a centrally apertured plate constituting saidjoint part, whereafier a radially slotted washer is interposed betweensaid nut and said plate and said nut is tightened downwardly onto saidwmher.

4. A method according to claim 3, wherein a radially slotted washer isplaced on top of said nut prior to the lowering of said second panel,and then said second panel is lowered towards said first panel asaforesaid until said slotted washer bears upwardly on a top wall of ashort horizontal tube of which the bottom wall is constituted by saidplate, whereafter, prior to the setting of said material, said nut isadjusted, if necessary, to adjust vertically said top wall and thus saidpanel, and, after the setting of said material, a radially slottedwasher is interbetween said nut and said plate and said nut Is tighteneddownwardly as aforesaid.

# l i i i

1. A method of joining together two pre-cast, vertical, concrete, wallpanels, comprising providing a first pre-cast, vertical, concrete wallpanel having a first concrete main body in which is embedded a firstattachment bar projecting upwardly from an upper horizontal edge of thebody, providing a second pre-cast, vertical, concrete, wall panel havinga second concrete main body in which is disposed a joint part, a secondattachment bar, and anchoring means, said joint part being disposed inthe second body in the region of a lower horizontal edge of that body,but projecting neither outwardly beyond said lower horizontal edge noroutwardly beyond two opposite, vertical, major faces of said secondbody, said second attachment bar being fixedly embedded in said secondbody and extending therethrough away from said joint part to an upperhorizontal edge of said second body, and said anchoring means beingfixedly embedded in said second body and being fixed to said joint partand extending within said second body from said joint part, the concreteof said second body not contacting said joint part to a detrimentalextent, applying a bed of unset setting material above the upperhorizontal edge of the first body, lowering said second panel with saidsecond attachment bar and said anchoring means fixedly embedded thereintowards said first panel such that said bed therebetween is squeezed andthat said joint part is displaced to a location below the upper end ofsaid first attachment bar, and, by way of an opening in one of saidmajor faces, fastening said first attachment bar to said joint part byfastening means applied between said first attachment bar and said jointpart and above said joint part.
 2. A method according to claim 1,wherein the fastening of said first attachment bar to said joint partcomprises tightening downwardly a fastening nut mounted onscrewthreading formed on the upper end zone of said first attachmentbar.
 3. A method according to claim 2, wherein said fastening nut hasbeen mounted on said screwthreading prior to the lowering of said secondpanel towards said first panel, and, during lowering, there is passeddownwardly over said nut a centrally apertured plate constituting saidjoint part, whereafter a radially slotted washer is interposed betweensaid nut and said plate and said nut is tightened downwardly onto saidwasher.
 4. A method according to claim 3, wherein a radially slottedwasher is placed on top of said nut prior to the lowering of said secondpanel, and then said second panel is lowered towards said first panel asaforesaid until said slotted washer bears upwardly on a top wall of ashort horizontal tube of which the bottom wall is constituted by saidplate, whereafter, prior to the setting of said material, said nut isadjusted, if necessary, to adjust vertically said top wall and thus saidpanel, and, after the setting of said material, a radially slottedwasher is interposed between said nut and said plate and said nut istightened downwardly as aforesaid.